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PubMed1986

Description of a novel microcomputer program to analyze left ventricular segmental wall motion during normal sinus rhythm and sinus tachycardia.

The authors have written a program to describe left ventricular (LV) regional wall motion (RWM) for a Tektronix 4051 graphic system and an MC68000, 32-bit word based microcomputer utilizing interactive graphics methods. Proper wall motion of 16 defined regions of the LV endocardial perimeter (RAO angiographic views) were computed from the magnitudes of fixed vectors fixed to analogous positions along the LV perimeter from end-diastole to end-systole (Figure 1). It was assumed that (1) LV contraction, tangential to the perimeter, produced RWM at large angles to the direction of contraction, and (2) LV contraction occurred uniformly along the anterolateral and posteromedial perimeters. All motion vectors were computed following digitization of the LV perimeters from projected images of 35-mm cineangiographic frames corrected for linear and nonlinear distortion. Digitization input was accurate to less than 0.3 mm and area computation demonstrated errors of less than 1.5%. A normal group (NG) without coronary artery (CA) disease (N = 31) defined a set of Gaussian distributed referent values for mean WM (magnitude of motion vectors) for all segments. WM amplitudes for the CA disease group (N = 125) demonstrated significant diviation in the areas supplied by occluded or stenosed coronary arteries. Qualitative and quantitative evaluation of the adequacy of coronary circulation and/or collateral vessel development could be made by inspection of WM amplitude computer plots. Proper WM was found to be highly specific for numbers and distribution of coronary arteries diseased.

Cineangiography↗
PubMed1978

[Recording the electrogram of the sinus node. Effects of the injection of tetrodotoxin into the artery of the sinus].

The cells of the SA node (SAN) are very resistant to the action of tetrodotoxine (TTX), a drug which. paradoxically, blocks depolarisation of the outer myocardial cells. Injection of TTX into the artery of the SAN brings about asystole; bur regular electrical activity, consisting of a slow wave of 200 to 300 ms duration, can still be picked up by an electrode placed on the SAN. This electrical activity, which can only be picked up over the SAN, and is resistant to TTX but blocked by acetylcholine, is interpretated as being the electrogram of the SAN. After the artery has been washed out by normal saline, the effect of TTX becomes progressively less; under these conditions, all degrees of sino-atrial block can be observed. Arising from a study of the phenomena of capture of the SA and AV nodes, of the effect of artrial stimulation, and of the time relationships between the various electrical events recorded, some hypotheses of the electrophysiology of the SAN and the sino-atrial conduction are put forward.

Acetylcholine↗